I am trying to make my fish do a semi-circle arch before it plunges in the water head first, but right now, it keeps landing on its back.
Also, is there a way to make the water splash (sprite 5) appear when the fish jumps out of the water?

Here's a link to the project you are trying to fix so that people can find it more easily:

https://scratch.mit.edu/projects/164435380/

I'll move this over to the “Help With Scripts” section for you - that's a better fit for this kind of topic

Here is the fix. I commented how I did it.
https://scratch.mit.edu/projects/164474946/

btw it's “arc”. An arch is a support structure which may include a shape that's similar to an arc, so they're sometimes confused. (Although in fact the shape of an arch is usually not part of a circle but a more complex shape called a catenary curve.)

Thanks everyone and yes I meant to say arc @gtoal!